In this proposal, the specific focus is the vocal communication and social behavior of free- ranging baboons (Papio cynocephalus ursinus) in the Okavango Delta, Botswana. Behavioral data will be collected on known individuals in 2-3 groups. Observations, tape-recordings, acoustic analyses, and field playback experiments will concentrate on 3 call types - the bark, wahoo, and grunt - that frequently elicit vocal replies, are often given in complex sequences, and share interesting phonetic properties with human speech sounds. Issues to be examined include patterns of answering among different group members, the use of answers in different contexts, and the acoustic structure of answers. The goals will be investigate the meaning of vocalizations in terms of both the information that listeners extract from a call and the mechanisms that underlie the signaler's production of a call. Additional studies will use playback experiments to test for the existence of reciprocal exchanges in alliances among baboon females, to examine baboons' antipredator behavior (particularly their alarm calls), and to investigate baboons' responses to the alarm calls of other species.